1. Field of the Invention
The present invention relates to an electrostatic flocking apparatus for electrostatically applying flock to a piece of work having an adhesive layer formed thereon (hereinafter referred to as the workpiece) when the workpiece is passed through at high speed an electrostatic flocking chamber in a condition in which the workpiece is electrically grounded, so that a so-called xe2x80x9celectrostatic flocking processxe2x80x9d is conducted, wherein the flocking process is followed by a drying process serving as an after treatment as is generally conducted to produce a flocked product.
2. Description of the Related Art
An electrostatic flocking apparatus has an essential construction in which: a flocking electrode for creating a high voltage electrostatic field is supported inside a housing through an insulation member, wherein the housing forms an electrostatic flocking chamber; a workpiece is oppositely disposed from, i.e., space a certain distance apart from the flocking electrode, and electrically grounded in a condition in which the workpiece is coated with an adhesive layer and disposed either above or below the flocking electrode, or disposed in the same plane or level as that of the flocking electrode; the electrostatic field is created between the flocking electrode and the workpiece, so that short fibers or fibrils are electrostatically floated and driven to fly parallel to the electric lines of force in the electric field toward the workpiece, whereby the short fibers are implanted in the adhesive layer of the workpiece. Then, the workpiece is subjected to an after treatment through which the workpiece is dried to become a flocked product. In fabrication, it is not unusual for the workpiece to be electrically grounded when the workpiece is supported on a shelf or suspended from an appropriate suspension member, provided both the shelf and the suspension member are electrically grounded. Further, it is also not unusual for the workpiece to be moved from an inlet opening of the housing to its outlet opening in a condition in which any supporing member for supporting the workpiece is used.
Provided in a ceiling portion of the housing is a ventilating apparatus provided with a filter, which filter prevents the floating short fibers from escaping outside from the housing in the electrostatic flocking operation.
Disposed on the side of the inlet opening of the housing is an adhesive applicator apparatus for applying an adhesive to a surface of the workpiece to form an adhesive layer thereon, through the adhesive applicator apparatus the workpiece is introduced into the housing.
Disposed on the side of the outlet opening of the housing is a drying apparatus for drying the flocked workpiece to perform an after treatment thereof when the flocked workpiece passes through the drying apparatus.
The drying apparatus is provided with: a heating unit for drying the adhesive layer having been formed on the surface of the workpiece; and, an exhaust port for discharging vapors or moisture contained in the adhesive layer of the flocked workpiece.
The drying apparatus is followed by a product receiving apparatus which receives the flocked products.
Now, the electrostatic flocking operation of the workpiece performed in a conventional electrostatic flocking apparatus will be described using a system called xe2x80x9cup-systemxe2x80x9d as an example, in which up-system a short fiber reservoir portion is disposed below the housing.
The so-called xe2x80x9cworkpiecexe2x80x9d is prepared by the use of the adhesive applicator apparatus disposed in front of the inlet opening of the housing, in which applicator apparatus an adhesive is applied to the surface of a piece of work being electrostatically flocked, so that an adhesive layer is formed on the work, whereby the work having been coated with the adhesive layer, i.e., the so-called xe2x80x9cworkpiecexe2x80x9d is prepared.
The thus prepared workpiece having the adhesive layer formed thereon is supported by a member having been electrically grounded, introduced into the housing through the inlet opening thereof, and disposed inside the housing. In other words, the workpiece is disposed inside the housing in a condition in which the workpiece is electrically grounded.
At this time, a high voltage is applied to the flocking electrode so that a high voltage electrostatic field is created. Consequently, due to the presence of this electrostatic field, electric lines of force extend from the flocking electrode to the electrically grounded workpiece.
Due to this phenomenon, the short fibers stored in the reservoir portion disposed inside the housing are floated and driven to fly toward the workpiece.
In order to enhance such floatation and flying motion of the short fibers toward the workpiece, a moisture bearing air is blown from the outside into the reservoir portion to permit the short fibers stored in the reservoir portion to take up moisture. Due to this, the short fibers floated in the housing are electrically charged and therefore strongly driven to rush for the workpiece. As a result, the short fibers have their front end portions stuck into the adhesive layer having been applied to the surface of the workpiece, so that the entire surface of the adhesive layer is uniformly covered with the short fibers.
Floating short fibers, which are left over to form excess fibers, reach the ceiling portion of the housing, and are trapped in a filter disposed in the ceiling portion of the housing, while the moisture bearing air is discharged to the outside through an exhaust unit.
The workpiece having subjected to the above operations emerges from the housing through its outlet opening, and then passed through the drying apparatus provided with the heating unit so that the moisture contained in the adhesive of the adhesive layer is evaporated, whereby the short fibers thus stuck in the adhesive layer are firmly implanted in the workpiece in this state.
After completion of the above process, the workpieces (i.e., completed products) are collected.
The electrostatic flocking operation should be performed to satisfy the following necessary conditions: the short fibers are uniformly implanted in the adhesive layer of the workpiece in a manner such that the short fibers are disposed perpendicularly to the surface of the workpiece; excess flocks (i.e., short fibers) are prevented from adhering to the adhesive layer; and, the time and electric energy are saved in the operation.
In a condition in which the housing (not shown) forming the electrostatic flocking chamber of the conventional flocking apparatus described above is not modified at all, the workpiece coated with the adhesive layer is electrically grounded. Under such circumstances, the workpiece is passed at a high speed higher than a predetermined speed through the housing to perform the flocking operation in minimal time in order to improve the operation in efficiency. However, it is impossible for such unmodified conventional flocking apparatus to produce a flocked product which is equal in quality to that produced in a condition in which the above-mentioned necessary conditions are satisfied. This is shown in FIG. 1. The reason why a phenomenon illustrated in FIG. 1 occurs is that: residence time of the workpiece 1 in the housing (i.e., electrostatic flocking chamber)in which the workpiece 1 is oppositely disposed from a flocking electrode 4 is reduced since the workpiece 1 passes through the housing at high speed. In other words, such high-speed transfer of the workpiece in the housing leads to lack of one of the above-mentioned necessary conditions, which one requires the workpiece 1 to stay in the housing for a predetermined period of time, in which housing an electrostatic field is created between the workpiece 1 and the flocking electrode 4. Further, an additional phenomenon occurs, in which the surface of the workpiece is subjected to the resistance of the air which is not expected. In addition, the short fibers 3, which float and move in a manner such that the front end portions of the short fibers 3 tend to be perpendicularly stuck in the adhesive layer of the workpiece, are obliquely stuck or implanted in the adhesive layer, as shown in FIG. 1, because the short fibers 3 tend to fall in a direction counter to the moving direction of the workpiece 1. In other words, when the workpiece 1 is passed through the housing at high speed, the amount of the short fibers 3 implanted in the workpiece reduces, which is disadvantageous in producing a soundly flocked product.
In order to surmount the above disadvantages, a voltage higher than that used in an ordinary case is applied to the electrode so that a high voltage electrostatic field is created to produce its strong electric lines of force between the workpiece and the electrode, whereby the short fibers are driven to fly toward the workpiece and to have their front end portions deeply stuck in the adhesive layer of the workpiece. However, the above flocking process is disadvantageous in failing to obtain a soundly flocked surface of the product which is poor in quality in spite of considerable consumption of both the electric power and the short fibers.
Further, it is not possible for the conventional drying apparatus used in the electrostatic flocking apparatus to perform a sound drying operation unless the drying apparatus is properly modified, because the transfer speed of the workpiece is too large.
It is an object of the present invention to provide an technological idea of obtaining a uniformly flocked product having short fibers implanted perpendicularly in its surface as is in the conventional case even when a workpiece coated with an adhesive layer is passed at high speed through both: a housing which forms an electrostatic flocking chamber of an electrostatic flocking apparatus, wherein the housing is modified to improve an electrostatic flocking operation in efficiency; and, a drying apparatus disposed adjacent to the housing.
In accordance with the present invention, the above object of the present invention is accomplished by providing:
In an electrostatic flocking chamber for forming an electrostatic flocking apparatus, comprising: a passage through which a workpiece passes at high speed and is subjected to an electrostatic flocking operation, wherein the workpiece enters an inlet opening of the passage of the chamber to travel across the chamber toward its outlet opening, the improvement wherein:
a distance between the inlet opening and the outlet opening is increased; and
the passage of the electrostatic flocking chamber permitting the workpiece to pass through is provided with a pair of electrodes both disposed parallel to the passage, wherein a first one of the electrodes is disposed in the side of the inlet opening and a high voltage is applied to the first electrode, and a second one of the electrodes is disposed in the side of the outlet opening and a low voltage is applied to the second electrode, the low voltage being lower than the high voltage.
Since the prevent invention has the above construction, it is possible to perform at high speed the electrostatic flocking operation, which operation permits the workpiece to pass through the housing at high speed, and is capable of obtaining the flocked product having the short fibers implanted perpendicularly to its surface.